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HNQ
6:22 AM
1
Q: Is there any physical evidence for motion?

SkeptronLet's say that we have 2 tennis balls in space, one being in motion (say, pushed by an astronaut), and the other one still. If we could take a snapshot of both tennis balls, would there be any evidence that could suggest that one is moving and the other one is still? Is there anything happening,...

 
 
2 hours later…
HNQ
8:24 AM
2
Q: Is tension always the same as centripetal force?

Oliver AbdulFor example, if a ball is attached to a string and released from a vertical height and then pivots around a point to initiate circular motion, tension is equal to centripetal motion. If, on the other hand, a ball hands from a string and it’s hit in such a way that it travels in a vertical circle...

2
Q: Why is Microwaved mac & cheese burnt where they touch?

Zooky After reheating cold about 1.5 oz. of Annie's Mac & Cheese shells for 15 seconds on high power in the microwave, the mac & cheese was burnt black only at certain points where the pasta is touching each other. Does anyone have an idea of what might be going on?

 
 
13 hours later…
HNQ
9:41 PM
1
Q: Does a quantum channel being time-translation invariant imply that its Kraus operators commute with the Hamiltonian?

glSLet $\mathcal E\in\mathrm{T}(\mathcal X,\mathcal Y)$ be a quantum channel (i.e. a completely positive, trace-preserving linear map sending states in $\mathrm{Lin}(\mathcal X,\mathcal X)$ into states in $\mathrm{Lin}(\mathcal Y,\mathcal Y)$). It is well known that any such map can be written in t...

 

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